Global Door Frame Metal Detector Market By Type (Single and Double Zones , 2 Zones to 18 Zones , 18 Zones to 27 Zones , and 27 Zones and Above), By Application (Transportation Facilities , Commericial Buildings , Institutional Buildings , and Military Facilities), By Region, and Key Companies - Industry Segment Outlook, Market Assessment, Competition Scenario, Trends and Forecast 2020-2029